It is known that a plurality of comb copolymers can be used as wetting and dispersing agents for solids, in particular pigments. Thus, comb copolymers are already known from the prior art that are obtained by converting styrene/maleic anhydride copolymers (SMA resins) as main chain with polyalkylene oxide amines and polyalkylene glycols as side chains.
For example, appropriately produced comb copolymers are described in U.S. Pat. No. 6,310,143 that besides imide structures have amide and ester linkages of the side chains with the main chain. Such comb copolymers do not assure a sufficiently high viscosity reduction as dispersing and wetting agents for some purposes of use, and as a result no adequately flowable pigment pastes can be formulated or no pigment pastes can be produced with a desired high pigment content.
Therefore, on the basis of this prior art there was a need to modify comb copolymers based on the known styrene-maleic anhydride copolymerisates so that by using them as wetting and dispersing agents solid pastes, preferably pigment pastes, with a very favourable flowability can be obtained in spite of the high solid content.